Hundreds of people have been killed in Abuja in recent years in attacks blamed on Boko Haram, including the bombing of a United Nations building which left 25 dead in 2011.

Nigeria’s secret police on Saturday said they had arrested a dozen suspects linked to the discovery of “sleeper cells” operated by Boko Haram militants in and around the capital Abuja.

The Department of State Services said those arrested had travelled from the restive northeast of the country to the Federal Capital Territory (FCT) and were planning on staging attacks in Abuja during the year-end festivities.

“Boko Haram…has continued to establish and operate sleeper cells whose (sole) mandates are to conduct surveillance and carry out subsequent attacks in the FCT,” the DSS said in a statement.

The statement listed the names of 12 suspected Boko Haram members, including a Niger national, who were arrested in Abuja and neighboring towns between October 29 and December 1.

The suspects hid in plain sight, often working in legal jobs while carrying out surveillance to “map out soft targets for attacks”, the statement added.

Hundreds of people have been killed in Abuja in recent years in attacks blamed on Boko Haram, including the bombing of a United Nations building which left 25 dead in 2011.

Overall, the group’s six-year old insurgency has killed some 17,000 people and displaced 2.5 million others, mostly in Nigeria.

Despite a regional military offensive against Boko Haram this year, its fighters have continued to stage guerrilla-style attacks in Nigeria and neighboring Niger, Chad and Cameroon.

A triple suicide bombing on an island in Lake Chad on Saturday killed at least 27 people, a Chadian security source said, in another apparent strike by Boko Haram.

Nigeria’s President Muhammadu Buhari has given his military commanders until the end of the year to end the insurgency, although he has admitted suicide and bomb attacks may continue.

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